“Evil is with us, it is that influence which tempts to sin, and which has been permitted to come into the world for the express purpose of giving us an opportunity of proving ourselves before God, before Jesus Christ, our Elder Brother, before the holy angels, and before all good men, that we are determined to overcome the evil, and cleave to the good, for the Lord has given us the ability to do so.”
(Brigham Young, Discourses of Brigham Young, p. 70).
Man is on earth under a plan provided by God, the Father of the spirits of men. This plan is for the good and welfare of man. The ultimate purpose of the plan is to enable every person to develop his every power, and thus to progress eternally.
Imbedded in every part of the plan is the right of every man to act for himself, to choose one or the other of the opposites which present themselves before him. If he chooses to do that which is for his welfare, which enables him to progress, he chooses the good. If he chooses that which retards his progress, he chooses the evil. Whatever conforms to the plan of God for His earth children is good; whatever is in opposition to the plan is evil. That is a simple, plain definition of evil
(John A. Widtsoe, Evidences and Reconciliations, pp. 205–6)